The pedometer is programmed to reset all step counts at midnight so you wake up the next morning and start at zero again. However if the clock on your pedometer is setup with AM/PM reversed, this resetting function could be triggered at noon instead. Your Pedometer only shows PM, so if you don’t see PM beside the clock it is displaying AM.
1) A follow-along setup video for your Pedometer (under 4 minutes)
2) A how to get the most accurate results on your Pedometer video